1. Field of the Invention
This invention relates generally to tinted or colored glass and, more particularly, to a blue-green colored soda-lime-silica glass having desirability for both architectural and vehicle glass applications.
2. Technical Considerations
It is known to provide glass compositions of various colors. For example, U.S. Pat. No. 5,214,008; U.S. Pat. No. 5,830,812; U.S. 2001/0025004; EP 0952123; and EP 0965570 disclose green or gray-green colored glass. EP 1031543A1; U.S. Pat. No. 2,956,892; U.S. Pat. No. 5,688,727; and U.S. Pat. No. 4,525,462 disclose blue colored glass. U.S. Pat. No. 2,755,212; U.S. Pat. No. 5,817,587; and WO 01/49622 disclose blue-green colored glass. These known glass compositions are useful for architectural glass, such as windows, insulated glass units, and the like, as well as for vehicle glass, such as automotive transparencies, e.g., windshields, side lights, back lights, moon roofs, sun roofs, privacy glass, and the like.
In order to achieve a desired color for a particular use, these known glass compositions contain various colorant materials. The primary colorant in typical blue or green colored glass compositions is iron, which is usually present in both the ferric (Fe2O3) and ferrous (FeO) forms. Other common colorants include cobalt, selenium, nickel, chromium, manganese, and titanium.
In producing conventional colored glass, such as conventional blue, green, or blue-green glass, the relative amounts of iron and the other colorants must be closely monitored and controlled within a specific operating range to provide the glass with the desired final color and spectral properties for a particular use. Varying the colorants outside this operating range can detrimentally affect the final color of the glass, the light transmittance characteristics of the glass, and the melting qualities of the glass composition. For example, increasing the amount of iron present in a particular glass composition can increase the difficulty of melting the glass batch materials, particularly in a continuous glass melting furnace, and can also decrease the visible light transmittance of the glass. Additionally, some of these known colored glass compositions contain selenium as one of the major colorants. However, a problem with selenium is that it is highly volatile at the temperatures used for conventional glass manufacture. The selenium can rapidly volatize before it can be incorporated into the glass and can thus affect the final glass color. Selenium volatilization can also lead to other production problems, such as unacceptable furnace emissions, color streaks, and poor color control.
It would be advantageous to provide a blue-green colored glass having desirable aesthetic and transmittance characteristics suitable for use with architectural glass and/or vehicle glass but which overcomes at least some of the drawbacks of known colored glass compositions.